Sound responsive coded signal demolition device



April 3, 1962 J. M. KENDALL SOUND RESPONSIVE CODED SIGNAL DEMOLITION DEVICE 2 Sheets-Sheet 1 Filed July 5, 1947 April 3, 1962 J. M. KENDALL SOUND RESPONSIVE CODED SIGNAL DEMOLITION DEVICE 2 Sheets-Sheet 2 Filed July 3, 1947 EEEEQ EEE w km EEK fi Eu S Q \h E W vm 5 EEC 5E m E E P m m R q NM t b ES mE m 3 i FW 290 ms Om mv On m 0 EEG:

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3,027,837 SOUND RESEGNSEVE QGDED SEGNAL DEMOLITKGN DEVKQE James M. Kendall, Coral Hills, Md. Naval Ordnance Laboratory, US. Naval Gun Factory, Washington, 116.)

Filed July 3, 1947, Ser. No. 758,970

9 Claims. {CL 102-18) (Granted under Title 35, US. Code (1952), sec. 266) This invention relates to a demolition device and more particularly to a demolition device adapted to be used as a component in a mine in which the device is employed to fire the mine in response to a coded signal comprising a series of groups of impulses received in predetermined time spaced relation from underwater explosions or signals such as may be produced by the use of depth charges, sonar signaling devices, or any other suitable signal device adapted to produce or initiate the production of underwater noise.

In certain of the devices of this character heretobefore devised for use with mines it has been the usual practice to employ ship counters and delayed arming devices. Such devices have not been found to be entirely satisfactory under all conditions of service for the reason that considerable difiiculty has been experienced in sweeping such mines within short periods of time by our forces by reason of the fact that, in the case of mines employing ship counters, the mine sweeping operation must be repeated until the ship counter has been actuated to a predetermined firing position and, in the case of mines employing delayed arming devices, the mines cannot be swept until the mine is armed at the completion of the arming period. Another disadvantage of these prior devices is that enemy forces can sweep mines having these devices once they understand the nature of the devices used in a particular mine field.

The foregoing disadvantages have been obviated by the demolition device of the present invention which is arranged to enable our forces to fire the mine instantly when a predetermined coded signal comprising a predetermined number of groups of impulses arranged in predetermined time spaced relation with respect to each other and each including a predetermined number of impulses, has been received from any suitable signal generating source. The arrangement of the present invention also prevents the mine from being swept by enemy forces who, though they may understand the nature of the sweep circuit, do not know what impulse signals correspond to the predetermined coded pattern.

One of the objects of the present invention is to provide a new and improved demolition device for use as a component of a mine for firing the mine in response to underwater coded signals which may be initiated at a remote distance from the mine.

Another object is to provide means for firing a mine in response to groups of impulse signals arranged in predetermined time spaced relation received through the water regardless of the armed condition of the mine.

Another object is to provide a demolition device for firing an explosive charge in response to a predetermined number of groups of signals received in predetermined time spaced relation and each having a predetermined number of signals.

A further object is to provide a new and improved demolition device responsive to a predetermined coded signal whereby a mine field employing mines having such devices is prevented from being swept by enemy forces who do not know what impulse signals correspond to the predetermined coded patterns of the several mines in the field.

3,@27,837 Patented Apr. 3, 1962 A still further object is to provide a new and improved demolition device which is selectively responsive to groups of coded impulses arranged in predetermined time spaced relation, is economical to manufacture, reliable in operation and which possesses all of the qualities of ruggedness and durability in service.

Additional objects, features, advantages, and improvements will become apparent from the following descrip tion of the preferred embodiment of the invention, taken in connection with the accompanying drawings, wherein:

FIG. 1 is a diagrammatic view of a complete electrical system for the demolition device of the present invention according to a preferred embodiment thereof and suitable for use in firing a mine;

FIG. 2 is a chart showing the firing cycle of operations of the components comprising the device as shown in FIG. 1 for a predetermined coded impulse pattern; and

FIG. 3 is a diagrammatic view of a fragmentary circuit which may be inserted between the points XY of FIG. 1 in lieu of the circuit components connected therebetween.

Referring now to the drawings on which like numerals of reference are employed to designate like parts throughout the several views and more particularly to FIG. 1 thereof, there is shown thereon a demolition device indicated generally by the numeral 10 which is well adapted for use with a marine mine to control the firing of the mine in response to a series of groups of impulses or waves of pressure received through the surrounding water by the vibration responsive sound pickup device D. The demolition device comprises a plurality of stepper switches SS-A, SS-B, SSC, time delay relays R1, R2, R3, reset relay R, and batteries B1, B2. The number of stepper switches and time delay relays used in a device corresponds to the predetermined number of groups of impulses to be used to fire the mine.

The stepper switches shown are of the Minor type and have been used extensively for many years in the telephone business. These switches comprise rotating arms 11, l2, l3, lock-in coils LI-A, LI-B, Ll-C, stepper coils SA, SB, SC, and a plurality of contacts on which the rotating arms impinge. The stepper coils cause the rotating arms of the stepper switches to move to the next succeeding contact whenever a coil receives an impulse. The stepper coils have off-normal contacts ON-A, ON-B, ON-C which are normally opened when the rotating arms are in Zero or home position. For all contacting positions of the rotating arms the off-normal contacts remain closed. In contradistinction to the conventional switch arrangement, the lock-in armatures of the stepper switches are so arranged that the lock-in coils Ll-A, LI-B, Ll-C, when energized, cause the rotating arms to be locked against returning movement from the position to which they have been moved by the stepper coils. When the lock-in coils are de-energized the lockin armatures are spring-urged out of locking position whereby the rotating arms are pulled back or returned to the zero or home position by springs which are attached thereto.

The thermal time delay relays R1, R2, R3 comprise bimetallic discs 30 which are adapted to snap between two positions in response to a predetermined temperature change, thereby to disconnect the stepper coil of one stepper switch and connect the stepper coil of the succeeding switch into the impulse circuit of battery B1. The reset relay R, which is generally of the same type as the aforedescribed time delay relays, has a normally closed armature 14. After relay R has been energized for a predetermined length of time, which for purposes of illustration has been selected to be two minutes in the particular embodiment of the demolition device described herein, the armature 14 will open, thereby breaking the circuit of battery B2. The operation of relays R, R1, R2, and R3 will become more clearly apparent as the description proceeds. These relays may be replaced by other time delay means such, for example, as those employing clockwork mechanisms.

The vibration responsive sound pickup device B may be of any type suitable for the purpose such, for example, as an anti-countermine switch preferably secured to the casing of the mine in which a pair of normally open contacts are brought into engagement with each other in response to a pressure signal or a shock received through the surrounding water. The explosive shock Wave which causes the contacts 15 of the sound pickup device D to close is of very short duration, perhaps only a few milliseconds, therefore the contacts are closed for a short period of time which is insufficient to operate the stepper coils. In order to prolong the energization of the stepper coils to approximately one tenth of a second, a circuit arrangement consisting of a condenser 16 and a small current limiting resistor 17 in series with the condenser is connected across the contacts 15 of the sound. pickup device D. The resistor prevents the welding together of the contacts 15 as the energy in condenser 16 is discharged therethrough on closure of the contacts in response to a signal. When contacts 15 open after a few milliseconds, the condenser is charged to the potential of battery B1, thereby causing current to flow in the circuit for energizing stepper coil SA, for example, which circuit: may be traced from the positive side of battery B1, condenser 16, resistor 17, conductor 18, stepper coil SA of stepper switch SS-A, conductor 2%, normally closed contact and armature 21 of time delay relay R1, and thence through conductor 22 back to the other side of battery B1. The arrangement of this circuit maintains a flow of current therein for a sufficient time to allow the stepper coil SA to actuate stepper switch SSA.

Two batteries B1 and B2 are provided in the demolition device disclosed herein. There is no drain on either of these two batteries unless the coded sweep circuit is set in operation in response to acoustic impulses.

In the operation of the demolition device, a sound impulse impinging on the sound pickup device D causes the normally open contacts 15 to come into engagement with each other, thereby to discharge condenser 16. When contacts 15 open, the battery B1 starts to recharge the condenser 16, thereby causing current to flow through and energize the stepper coil SA of stepper switch SS-A in the aforedescribed manner. When the stepper coil SA is thus energized in response to the first impulse in a first group of impulses, the rotating arm 11 advances to position one on its associated contact bank. Concurrently with the advancement of arm 11 onto contact 1, the contacts of the ofi-normal switch ON-A of stepper switch SS-A close, thereby completing the circuit from battery B2 which causes current to flow through the three lock-in coils LIA, LI- B, LLC, the heater coil 23 of time delay relay R1, and the heater coil 24 of reset relay R. This circuit can be traced from the positive side of battery B2 by way of conductor 25, through coils LI-A, LI-B, LI-C and heater coils 23 and 24 in parallel to conductor 26, and thence through switch ON-A, conductor 18, and armature 14 and contact of reset relay R to the other side of battery B2.

When the second impulse in the first group of impulses is sent through the water about one second after the first one, the rotating arm 11 is advanced to position two on the contact bank of stepper switch SS-A. Similarly, successive impulses following in approximately one second intervals advance the arm 11 to positions three and four on the contact bank. Contact 4 has a conductor 27 connected to the stepper coil SB of the next stepper switch SS-B. Fifteen seconds after the first impulse of the first group of impulses comes through the water, the heater coil 23 of time delay relay R1 is heated to a predetermined temperature which causes the disc Ziti to change position. The disc, in turn, acts through an element 19 to cause armature 21 of relay R1 to disengage its break contact connected to conductor 26 and engage its make contact connected to conductor 28, thereby completing a circuit for energizing stepper coil SE of stepper switch SS-B from battery B1 as contacts 15 of pickup device D open after the first impulse of a second group of impulses has been received by the pickup device. This circuit can be traced from the positive side of battery B1, condenser 16, resistor 17, conductor 18, rotating arm 11 and contact 4 of switch SSA, conductor 27, stepper coil SB, conductor 2& armature 31 and break contact of time delay relay R2, conductor 28, armature 21 and make con-tact of time delay relay R1, and conductor 22 to the other side of battery B1. As stepper coil SE is energized in response to the first impulse in the second group of impulses in the aforedescribed manner, the rotating arm 12 is advanced onto contact 1 on the contact bank of stepper switch SS-B.

Concurrently with the advancement of arm 12 onto its associated contact bank, the contacts of the off-normal switch ON-B of stepper switch SSB close, thereby completing a circuit from battery BZ-Which causes current to flow through the heater coil 32 of time delay relay R2. This circuit may be traced from the positive side of battery B2 by way of conductor 25, heater coil 32, switch O N-B, conductor 27, contact 4 and rota-ting arm 11 of switch SS-A, conductor 18, and armature 14 and contact of reset relay R to the other side of battery B2.

When the second impulse of the second group of impulses comes through the water about one second after the first one of the second group of impulses which has caused arm 12 to move onto the contact bank of stepper switch SSB, the rotating arm 12 advances to position two of the contact bank of stepper switch SSB. Contact 2 has a conductor 33 connected to one side of the stepper coil SC of the next stepper switch SSC. Fifteen seconds after the first impulse of the second group of impulses comes through the water, the heater coil 32 of time delay relay R2 is heated to a predetermined temperature which causes disc 30 thereof to change position and act through element 19 to cause armature 31 of relay R2 to disengage its break contact connected to conductor 29 and engage its make contact connected to conductor 35, thereby completing a circuit for energizing stepper coil SC of stepper switch SS-C from battery B1 as contacts 15 of pickup device D open after the first impulse of the third group of impulses has been received by the pickup device. This circuit can be traced from the positive side of battery B1, condenser 16, resistor 17,-conductor 18, rotating arm 11 and contact 4 of switch SS-A, conductor 27, rotating arm 12 and contact 2 of switch SS-B, conductor 33, stepper coil SC, conductor 36, armature 37 and break contact of time delay relay R3, conductor 35, armature 31 and make contact of time delay relay R2, conductor 28, armature 2 1 and make contact of time delay relay R1, and conductor 22 back to the other side of battery B1. As stepper coil SC is energized in response to the first impulse of the third group of impulses in the aforedescribed manner, rotating arm 13 is advanced onto contact 1 on the contact bank of stepper switch SSC.

Concurrently with the advancement of arm 13 onto contact 1 of its associated contact bank, the contacts of the off-normal switch ONC of the stepper coil SC close, thereby completing a circuit from battery B2 which causes current to flow through the heater coil 34 of time delay relay R3. This circuit can be traced from positive battery B2, by way of conductor 25, heater coil 34, switch ON-C, conductor 33, contact 2 and rotating arm 12 of switch SS-B, conductor 27, contact 4 and rotating arm 11 of switch SSA, conductor 13, and armature 14 and contact of reset relay R to the other side of battery B2. After five impulses of the third group of impulses have come through the water in one second intervals, the rotating arm 13 is advanced to position five on the contact bank of stepper switch SS-C. Contact 5 has a conductor connected to one side of the detonator DE. Fifteen seconds after the first impulse of the third group of impulses has been received through the water, the heater coil 34 of time delay relay R3 is heated to a predetermined temperature which will cause disc 39 to change position and act through element 19 to cause armature 37 of relay R3 to disengage its break contact connected to conductor 36 and engage its make contact connected to conductor 39, thereby completing a circuit for energizing detonator DE from battery B1 as contacts 15 of pickup device D open after an additional impulse has been received by the pickup device. This circuit may be traced from the positive side of battery B1, condenser 16, resistor 17, conductor 18, rotating arm 11 and contact 4- of switch SS-A, conductor 27, rotating arm 12 and contact 2 of switch SS-B, conductor 33, rotating arm' 13 and contact 5 of switch SS-C, conductor 38, detonator DE, conductor 39, armature 37 and make contact of time delay relay R3, conductor 35, armature 31 and make contact of time delay relay R2, conductor 28, armature 21 and make contact of time delay relay R1, and conductor 22 back to the other side of battery B1. As the detonator is energized in response to the additional impulse, the detonator is fired and the mine is exploded, thereby to complete a firing cycle of operations of the sweep circuit.

The impulse code 4251 has been selected to illustrate the operation of the aforescribed sweep circuit of the demolition device. Any other sequence of impulses would not have completed the battery B1 circuit to the detonator DE. For example, in the first group of impulses, if any number of impulses but four were used, the rotating arm 11 of stepper switch SS-A would not have stopped on contact four of the stepper switch which has conductor 27 connected to the stepper coil SB of the next stepper switch SS-B. Therefore, no matter what further sequence of impulses would be applied to the circuit the aforetraced firing circuit for detonator DE could not be completed during the period of time measured by relay R for the reason that the firing circuit must be completed through arm 11 and contact 4 of switch SS-A for the particular circuit arrangement of FIG. 1 which has been connected to operate on the code 4251. The normally closed reset relay R has a predetermined time delay of two minutes, after which disc 43 thereof changes position and acts through element 44 to disengage armature 14 of relay R from its break contact, thereby to open the aforetraced circuits for energizing the three lock-in coils LI-A, LI-B, LIC and the four relay coils 24, 23, 32 and 34 from battery B2. As the lock-in coils are de-energized, rotating arms 11, 12, and 13 of stepper switches SSA, SS-B, and SS-C respectively, drop back to the zero or home positions of the contact banks. As the switch arms are returned to their home positions, off-normal switches ON-A, 0N-B and ON-C are opened, thereby to additionally open the circuits for energizing relay coils 24, 23, 32, and 34 whereby the coils are not re-energized as armature 14 again engages its break contact when disc 43 snaps back to its initial position after relay R has cooled a sufficient amount. Armatures 21, 31, and 37 also re-engage their break contacts as discs 30 individual thereto snap back to their initial positions in response to a sufficient cooling of relays R1, R2, and R3, thereby to restore the sweep circuit to its initial condition and in readiness for operation in response to a succeeding coded signal.

The firing cycle of the aforedescribed operations of the components comprising the coded impulse sweep circuit is illustrated graphically in FIG. 2. The vertical lines indicate the time in seconds elapsed after the first impulse acts on the sound pickup device D. The 60 seconds line 41 shows the last impulse which fires the mine. At that time all the components of the device would be destroyed, therefore, the horizontal lines on the time chart are shown dotted after the 60 second interval. When the first impulse of the first group of impulses is received, the contacts 15 of pickup device close as indicated at 45 on the chart of FIG. 2. As contacts 15 open, the stepper coil of switch SS-A is operated and rotating arm 11 thereof moves onto contact 1 of the switch. Simultaneously therewith, the ofi-normal switch ON-A is closed as indicated by the line 46 on the chart. As switch ON-A closes, lock-in coils Ll-A, LI-B, and LI-C of switches SS-A, SS-B, and SS-C respectively, and coils 23 and 24 of relays R1 and R respectively, are simultaneously energized as indicated by the lines 47, 48, 49, 51, and 52 respectively. Fifteen seconds after the operation of device D at 45, relay R1 has heated sufficiently by reason of the energization of coil 23 thereof to cause the armature 21 to be transferred from its break contact indicated by the line 53 to its make contact indicated by the line 54. When this occurs, the circuit for operating stepper coil SA from battery B1 is interrupted and further operation of switch SS-A during the present firing cycle of operations is no longer possible. Within this 15 second interval, 3 additional impulses producing operations of pickup device D, as indicated on the chart at 55, 56, and 57 respectively, must be received in order to advance rotating arm 11 of switch SS-A to contact 4 on the contact bank of the switch. It is not essential, however, that the 4 impulses of the first group of impulses be received in any particular sequence or time spaced relation with re spect to each other. The essential requirement is that 4 impulses, no more and no less, all be received within the 15 second interval.

As armature 21 of relay R1 engages its make contact, stepper coil SE of switch SS-B is in readiness to be operated as contacts 15 of pickup device D open after operation of the device in response to the first impulse of the second group of impulses received through the surrounding water. When this operation of pickup device occurs, as indicated at 58 on the chart, rotating arm 12 of switch 83-13 is moved onto contact 1 of the contact bank thereof and, simultaneously therewith, the off-normal switch ON-B is closed as indicated at 59 on the chart. As this switch is closed, coil 32 of relay R2 is energized as indicated at 61 on the chart. Fifteen seconds after operation of pickup device D at 58, relay R2 has heated sufiiciently by reason of the energization of the coil 32 thereof to cause armature 31 to be transferred between the break and make contacts thereof as indicated at 62 and 63 respectively on the chart. As armature 31 engages its make contact, the circuit for operating stepper coil SE of switch SSB from battery B1 is interrupted. Accordingly, the additional operation of stepper coil SB and the advancement of rotating arm 12 to contact 2 on its associated contact bank must occur within the 15 second interval provided by relay R2. The additional operation of pickup device for this purpose is indicated at 64 on the chart. No particular time spaced relation of the operations 58 and 64 of the pickup device within this second 15 second interval is required. It is essential, however, that two operations, no more and no less, occur within this 15 second interval in order that arm 12 be advanced to, and stop at, contact 2 of switch SSB.

As armature 31 engages its make contact, stepper coil SC of switch SS-C is in readiness to be operated as contacts 15 of pickup device D open after the device has been operated in response to the first impulse of the third group of impulses. When this impulse is received, as indicated by the operation of device D at 65 on the chart, rotating arm 13 of switch SS-C moves onto contact 1 of its associated contact bank and, simultaneously therewith, oft-normal switch ON-C is closed as indicated at 66 on the chart. As this off-normal switch is closed, coil 34 of relay R3 is energized as indicated at 67 on the chart. Fifteen seconds after operation of device D at 65, relay R3 has heated sufiiciently by reason of the energization of coil 34 thereof to cause armature 37 to be transferred from its break contact indicated at 68 on the chart to its make contact indicated at 69 on the chart. Within this 15 second interval, 4'additional impulses, no more and no less, must be received as indicated by the operation of pickup device 71, 72, 73, and 74 on the chart, in order that rotating arm 13 of switch SS-C be advanced to and stop at contact on its associated contact bank, thereby to place the detonator DE in a condition to be fired after pickup device D has been operated as at 75 on the chart in response to an additional impulse received through the water.

Two minutes after operation of device D at 45, relay R has been heated sufficiently by reason of the energization of coil 24 thereof to cause armature 14 of the relay to disengage its break contact, indicated at 42 on the chart, whereupon the circuits for maintaining operation of the lock-in coils are interrupted and the rotating arms of the stepper switches are returned to their home positions. After an additional period of time of approximately 60 seconds, not indicated on the chart and of sufiicien't duration to cool relays R, R1, R2, and R3, their respective armatures re-engage their break contacts, thereby to restore the sweep circuit to its initial condition.

It will be noted that the second and third 15 second intervals, during which the second and third groups of impulses respectively are received, begin as the first impulses of these groups are received and need not follow the first and second 15 second intervals respectively in any particular predetermined time spaced relation providing that the intervals occur in sequence Within the two minute interval provided by relay R and that sufi'l- .Cien-t additional time be allowed for the firing of detonator DE within the two minute interval. In the event that the improper sequence of groups of impulses and the improper number of impulses per group were used in trying to sweep the mine, the firing circuit would not be completed to the detonator DE for the aforedescribed reasons and the normally closed reset relay R would restore the sweep circuit to its initial condition 120 seconds after the first impulse of the first group of impulses is received. The chart on FIG. 2 shows very clearly that since the three time delay relays R1, R2, R3 used in this embodiment of the subject invention have 15 second delays, that is, current must flow in the heater coils 23, 32, 34 for approximately 15 seconds before the relays will be actuated, there is ample time for the use of ten impulses in each of the three groups of impulses. In a demolition device of the type described using three stepper switches, each with a contact bank of ten contacts, there are 1000 combinations of firing order or codes possible. In a device with four stepper switches, each with a contact bank of ten contacts, it is possible to wire the switches so as to fire the mine in response to a particular selected one of 10,000 diiferent combinations of wiring connections between the switches. The enemy would have a difficult time sweeping mines equipped with coded impulse sweep circuits of the character described unless he knew the signal code which corresponded to a particular setting of the sweep circuits of the mines. Our forces, however, knowing the signal code would have no difficulty sweeping the mines.

In the event that the enemy attempts to wear out the coded impulse sweep circuits of mines by sending frequent acoustic signals into the mine field, he will, at most, succeed in wearing out the batteries B1 and B2 in said sweep circuits thereby rendering the coded sweep circuit inoperative. However, the influence firing feature of the mine would not be affected by the wearing out of batteries B1 and B2. With good batteries, especially E2, the enemy would have to fire many acoustic signals and spend a great deal of time before rendering the sweep circuit inoperative. Where a mine field has been laid with mines having sweep circuits responsive to different codes, the accidental demolition of a group of mines in 0 response to a fortuitous coded signal initiated by the enemy might lead the enemy to believe that all mines in the field have been swept in response to his sweeping operations, whereas the waters would in fact be fatal to his shipping by reason of the remaining unexploded mines within the mined area. v

Referring now to FIG. 3, a circuit arrangement 18 provided which decreases the possibility of contacts 15 of pickup device D being welded by the discharge of condenser 16 therethrough. This is accomplished by employing a telephone type relay RT whose armature '76 is caused to engage its make contact in response to a relatively small current supplied to the operating coil of the relay through an obvious circuit as condenser 16 charges from battery B1 after contacts 15 have opened. In this case, the capacityof condenser 16 maybe considerably smaller, thereby reducing the value of the current discharged through contacts 15. As relay RT operates, positive potential of battery B1 is applied to conductor 18 through armature 76 and its make contact, whereby the relatively greater current required for operation of the stepper coils is supplied directly from battery B1, rather than through condenser 16 as before. The condenser, however, in each case controls the duration of energization of the stepper coils Whose operating circuits are opened as the relay contacts open when the condenser approaches its fully charged condition.

It should now be apparent from the foregoing description that a demolition device has been provided which is well adapted to fulfill the aforesaid objects of the invention and although the invention has been described in particularity with reference to one example thereof which gives satisfactory results, it readily will be apparent to those skilled in the art to which the invention pertains, after understanding the invention, that various changes, modifications, and embodiments may be made without departing from the spirit and scope of the invention, and it is intended therefore, to cover all such changes in the claims appended hereto.

The invention herein described and claimed may be manufactured and used by or for the Government of the United States of America for governmental purposes without payment of any royalties thereon or therefor.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. In a demolition device having a signal pickup device responsive to acoustic signals received through the surrounding water and an electroresponsive detonator, the combination comprising, first, second and third stepper switches each comprising a wiper arm and a cooperating contact bank, means adapted to be controlled by said pickup device for rendering the first stepper switch effective to advance its wiper arm to successive contacts on its associated switch bank in response to a first group of impulses received by the pickup device, means adapted to be controlled by said pickup device for rendering the second stepper switch eifective to advance its wiper arm to successive contacts on its cooperating contact bank in response to a second group of impulses received by the pickup device when the wiper of the first switch is moved to a predetermined contact on its associated switch bank, the predetermined contact of said first switch electrically connecting the wiper arms of said first and second switches, means adapted to be controlled by the pickup device for rendering a third switch effective to advance its wiper arm to successive contacts on its cooperating contact bank in response to a third group of impulses received by the pickup device when the wiper of the second switch has been moved into engagement with a predetermined contact on its cooperating contact bank, the predetermined contact of said second switch electrically connecting the wiper arms of. said first, second and third switch, and a firing circuit for the detonator including the electrically connected wiper arms of said switches and adapted to be rendered eifective to fire the detonator under control of the pickup device in response to the next succeeding impulse received thereby after the wiper of the third switch has been moved into engagement with a predetermined contact on its cooperating contact bank.

2. In a demolition device having a signal pickup device responsive to acoustic impulses received from the surrounding water and an electroresponsive detonator, the combination comprising, first, second, and third stepper switches each having a contact bank, a spring biased wiper arm initially positioned off the contact bank, and means including a lock-in coil adapted when energized to prevent returning movement of the wiper arm to the initial position thereof from an advanced position on the contact bank; means adapted to be controlled by the pickup device for consecutively rendering the switches efiective to advance the wiper thereof to successive contacts on their cooperating contact banks in response to first, second, and third groups of signals received by the pickup device when the wipers of the first and second switches have been moved to predetermined contacts individual thereto by said first and second groups of signals respectively, said predetermined contacts serially connecting the wipers of said first, second, and third switches; means effective as the wiper arm of the first switch moves onto its contact bank for energizing the lock-in coils of the switches; first and second, third, and fourth timing means adapted to be rendered effective to measure predetermined intervals of time respectively as the wipers of the first, second, and third switches move onto their cooperating contact banks; means controlled by the second, third, and fourth timing means for respectively rendering the first, second, and third switches inefiective to advance the wiper arms thereof in response to signals received by the pickup device at the termination of the intervals of time measured by the second, third, and fourth timing means; a firing circuit for the detonator including said wiper arms connected in series and adapted to be rendered effective to fire the detonator under control of the pickup device in response to the next succeeding impulse received after the third group of impulses has been received thereby when the wiper arm of the third switch is positioned on a predetermined contact of its associated contact bank at the termination of the timing interval measured by the fourth timing means and when the last named impulse is received within the predetermined interval measured by said first timing means; and means controlled by said first timing means for de-energizing said lock-in coils at the termination of the time interval measured by said first timing means.

3. In a demolition device having a pickup device responsive to acoustic signals received through the surrounding water and an electroresponsive detonator, the combination of first, second, and third stepper switches each comprising a wiper arm and a cooperating contact bank; an input circuit for said stepper switches adapted to be operatively responsive to said pickup device to produce electrical impulses correlative with the signals received by said pickup device; a first time-controlled means con trolled by said input circuit for rendering the first stepper switch efiective to advance its wiper arm to successive contacts on its associated switch bank in response to a first group of impulses produced by said input circuit in response to a first group of signals received by the pickup device within a predetermined period of time; a second timecontrolled means controlled by said input circuit for rendering the second switch effective to advance its wiper arm to successive contacts on its cooperating contact bank in response to a second group of impulses produced by said input circuit in response to a second group of signals received by the pickup device within a second predetermined period of time when the wiper of the first switch is in engagement with a predetermined contact on its associated switch bank at the termination of said first predetermined period of time, the predetermined contact of said first switch connecting said input circuit to said second time-controlled means; a third time-controlled means controlled by said input circuit for rendering the third switch effective to advance its wiper arm to successive contacts on its cooperating contact bank in response to a third group of impulses produced by said input circuit in response to a third group of signals received by the pickup device within a third predetermined period of time when the wiper of the second switch is in engagement with a predetermined contact on its cooperating contact bank at the termination of said second predetermined period of time, the wiper and predetermined contact of said second switch connecting said third time-controlled means to said input circuit through the wiper and predetermined contact of said first switch; and a firing circuit for the detonator including the wiper arms of said switches and adapted to be rendered efiective to fire the detonator under control of the input circuit in response to the next succeeding impulse produced in response to a signal received by said pickup device after the termination of said third predetermined period of time and when the wiper of the third switch is in engagement with a predetermined contact on its operating contact bank at the termination of the third pretermined period of time, the wiper and predetermined contact of said third switch connecting said input circuit to said firing circuit through the wipers and the aforementioned predetermined contacts of said first and second switches.

4. In a demolition device having a pickup device responsive to acoustic signals received through the surrounding water and an electroresponsive detonator, the combination comprising, first, second, and third stepper switches each comprising a wiper arm and a cooperating contact bank; an input circuit for said stepper switches adapted to be operatively responsive to said pickup device to produce electrical impulses correlative with the signals received by said pickup device; first, second, and third timing means individual to said stepper switches and each adapted to measure a predetermined interval of time; means individual to said stepper switches for setting said timing means individual thereto in operation as the respective wiper arms of the switches move onto their associated contact banks; a plurality of circuits respectively controlled by the pickup device for rendering the stepper switches eiiective to advance the wipers thereof to successive contacts on their associated contact bank and adapted to fire the detonator in response to first, second, third, and fourth groups of impulses produced by said input circuit in response to first, second, third and fourth groups of signals received in consecutive order by the pickup device; a firing circuit adapted to be rendered effective to fire the detonator; and a plurality of switch means controlled respectively by said first, second, and third timing means for consecutively transferring control of said input circuit from switch to switch at the termination of the time intervals respectively measured thereby when the wiper arms of the switches are in engagement with predetermined contacts on their associated contact banks at the termination of said intervals and thence to said firing circuit when the wiper arm of said third stepper switch is in engagement with a predetermined contact on its associated contact bank at the termination of the time interval of said third timing means.

5. In a circuit closing device controlled by a predetermined number of predetermined groups of signals received by the device in predetermined time intervals, the combination of circuit means connected to the input side of said device for electrically connecting the device to a signal responsive pickup device, a first circuit including first, second, and third stepper switches serially connected to one another and each comprising a spring biased wiper arm and a cooperating contact bank, a second circuit including a plurality of coils each of which is individual to one stepper switch for locking the wiper thereof in an advanced position on the bank when the coil is energized,

first, second, and third timing switch means individual to the first, second, and third stepper switches and each comprising a bi-metallic disc, a heater coil therefor, and a pair of transfer contacts adapted to be operated by the disc when the coil has been energized for a predetermined interval of time, heater coil circuit means for energizing the coils of the timing means individual to the switches as the wiper arms of the switches move onto their respective contact banks, circuit means including said transfer contacts for successively controlling the step by step operation of the first, second, and third stepper switches under control of the pickup device in response to first, second, and third groups of impulses received thereby and adapted to successively connect the wiper arms of the switches in series as the transfer contacts of the first, second, and third timing means are operated successively and a fourth timing switch means having a bi-metallic disc, a coil for heating the disc adapted to be energized by said heater coil circuit means as the wiper of the first switch moves onto its contact bank, and a pair of nor mally closed contacts in said locking circuit and adapted to be opened by the disc when the coil has been energized for a predetermined interval of time thereby to de-energize said locking coils and restore the wipers of the switches to the initial positions thereof as the contacts open.

6. A circuit closing device controlled by a predetermined number of groups of signals each having a predetermined number of signals and received by the device in predetermined sequential intervals of time and within a predetermined time period including said intervals of time, comprising a plurality of stepper switch assemblies including predetermined contacts of the respective contact banks thereof connected to establish a series connection to one side of a current source when the switch assemblies have operated in response to said signals, a plurality of stepper switch actuating circuits respectively including a plurality of stepper coils and operatively connected to the switch assemblies individual thereto for causing actuation thereof, said actuating circuits also respectively including a plurality of time-delay switch means respectively operable in said predetermined sequence and in said predetermined intervals of time for sequentially by-passing the stepper coils individual thereto in accordance with the sequential lapse of the predetermined intervals of time, said time-delay switch means establishing a series connection to the other side of said current source when all of said time-delay switch means have operated, time-delay reset means for measuring said predetermined period of time when set in operation, a lock-in coil circuit including said time-delay reset means and a plurality of lock-in coils respectively and operatively connected to the stepper switch assemblies and operable as a first of the stepper coils operates, a plurality of time-delay switch actuating circuits operatively connected to said time-delay switch means respectively and to said switch assemblies for setting said time-delay switch means in operation as the switch assemblies individual thereto operate, said timedelay reset means including a normally closed switch in said lock-in coil circuit for resetting the device to the initial condition thereof as said normally closed switch opens when said predetermined time period elapses, an output terminal for connection to an electroresponsive device comprising a predetermined contact of the contact bank of the last stepper switch assembly to be operated and included in said series connection thereof, and a contact on the last operated one of said time-delay switch means and included in said series connection established thereby and adapted to be connected to the other side of the electroresponsive device.

7. A device of the character disclosed comprising multiple stages of control circuits, each of said stages including a stepper switch assembly for actuation of the switch assembly individual thereto in response to signal impulses received thereby, time-delay switch means operatively connected to said switch assembly for by-passing said switch assembly and connecting the corresponding switch assembly of the next succeeding stage to the return conductor of the switch assembly of the preceding stage after a predetermined time interval measured by said. time delay switch means has elapsed, circuit means for connecting a predetermined step-contact on the stepper switch assembly of each stage with the input terminal of the stepper switch assembly of said succeeding stage, and a predetermined step-contact of the stepper switch assembly of said suceeding stage serving as an output terminal of the device.

8. A selector device for progressively connecting an electroresponsive device into conducting relationship in a circuit in response to a series of groups of impulses received as a coded signal and arranged in predetermined time spaced relation comprising an input terminal adapted to be connected to a signal receiving device for connecting said terminal to a source of current in response to each impulse received by said signal receiving device, a plurality of stepper switch assemblies serially connected to said input terminal, a plurality of stepper switch actuating coils respectively connected on the input sides thereof to the input conductors of said stepper switchassemblies individual thereto and operatively connected to said stepper switch assemblies, a plurality of time-delay transfer relays having the break contacts thereof respectively connected to the output sides of said actuating coils and having the make contacts and armatures of all except the last actuated one of the relays operatively connected to the output sides of the coils of the next succeeding stepper switch assemblies at the termination of the time intervals respectively measured thereby, circuit means for sequentially actuating said time-delay relays as the switch assemblies individual thereto are operated, an output terminal connected to a predetermined one of the contacts on the contact bank of the last of said serially connected stepper switch assemblies for connection to the input side of an electroresponsive device, and a return path for said selector device including the make contacts and the armatures of all of said time-delay relays in series connection therein and a terminal adapted to be connected to the negative side of the current source.

9. A selector device of the character disclosed and operable in response to coded signals received by a signal responsive device comprising, in combination, a plurality of time measuring switch means, a plurality of stepper switches individual to said time measuring means for setting the time measuring means in operation individually as the stepper switches individual thereto are operated, circuit means including said time measuring switch means and operable from said signal responsive device for operating said stepper switches in sequence and for advancing the wipers thereof ahead one step on the contact banks thereof for each signal received by the signal responsive device during the time intervals measured by the switch means individual thereto, and an output circuit including the respective wipers and predetermined contacts of said stepper switches connectable in series connection when no more and no less than a predetermined number of steps have been taken by said stepper switches during said time intervals individual thereto.

References Cited in the file of this patent UNITED STATES PATENTS 1,331,151 Hopkins Feb. 17, 1920 1,814,524 Nelson July 14, 1931 2,255,162 Hart Sept. 9, 1941 2,368,953 Walsh Feb. 6, 1945 2,411,091 Henderson Nov. 12, 1946 2,441,145 Hansen a May 11, 1948 2,480,624 Barnard et a1 Aug. 30, 1949 2,497,656 Clarke Feb. 14, 1950 

